RssWatcher

v0.1.0

RssWatcher v0.1.0 RssWatcher View Source

A small worker that watches a single RSS feed, parses the changes, and dispatches updates.

Installation

Dependencies

Add the following to your dependencies:

{:rss_watcher, "~> 0.1.0"}

For easy mode, you can use the default adapters to fetch and parse RSS feeds. Just add the following to your dependancies, and you should be good to go.

{:tesla, "~> 1.2.1"}, # For HTTP requests
{:fiet, "~> 0.2.1"}, # For RSS parsing
{:timex, "~> 3.0"}, # For timestamp parsing

And add Timex to your list of applications.

extra_applications: [ ...,  :timex]

Adapters

RssWatcher.HTTP.Tesla is provided by default. To use, add the following dependancies to your dependency list. See module configuration around middleware, and additional adapter options.

{:tesla, "~> 1.2.1"}

For RSS parsing, RssWatcher.Feed.Fiet is provided by default, and handles parsing XML and timestamps. To use, add the following dependencies to your dependency list.

{:fiet, "~> 0.2.1"},
{:timex, "~> 3.0"}

And add timex to your list of applications.

extra_applications: [ ...  :timex]

Link to this section Summary

Types

callback()
options()
url()

Functions

child_spec(init_arg)

Returns a specification to start this module under a supervisor.

start_link(options)

RssWatcher is a worker, so the recommended usage is to add it as a child to your supervisor.

Link to this section Types

Link to this type

callback() View Source 
callback() :: {module(), atom()} | function()

Link to this type

options() View Source 
options() :: [{:refresh_interval, integer()}]

Link to this type

url() View Source 
url() :: String.t()

Link to this section Functions

Link to this function

child_spec(init_arg) View Source

Returns a specification to start this module under a supervisor.

See Supervisor.

Link to this function

start_link(options) View Source (since 0.1.0) 
start_link(Keyword.t()) :: :ignore | {:error, any()} | {:ok, pid()}

RssWatcher is a worker, so the recommended usage is to add it as a child to your supervisor.

API Example 

children = [
  {RssWatcher,
      url: "http://example.com/rss",
      callback: {Notifications, broadcast, ["#channel_id"]}
  }
]

Supervisor.start_link(children, strategy: :one_for_one))

Or, with a dynamic supervisor:


children = [
  {DynamicSupervisor, strategy: :one_for_one, name: MyApp.RssSupervisor}
]

Supervisor.start_link(children, strategy: :one_for_one)

...

DynamicSupervisor.start_child(
  MyApp.RssSupervisor,
  {
    RssWatcher,
      url: "http://example.com/rss",
      callback: {Notifications, broadcast, ["#channel_id"]}
  }
)

Each RssWatcher worker requires at least a url, and a callback. Additional configuration can be provided to use alternate adapters.

Url (required)

The url should be a string, which resolves to an RSS feed.

Callback (required)

The callback can be in the form of {module, function, arguments}, or an anonymous/suspended function.

If {module, function, arguments} format, the callback will be dispatched with an additional argument - the parsed XML. Otherwise, the parsed XML will be the only argument provided. See below for examples.

Additional Configuration

The configuration is provided as a keyword list. The available options (and their defaults) are listed below

  • :refresh_interval - integer. How often the feed is checked, in seconds. Defautls to 60.
  • :rss_parser - Atom/RSS 2.0 parser module. Defaults to RssWatcher.Feed.Fiet,
  • :rss_parser_options- options for the above parser. Defaults to [],
  • :http_client - HTTP client for fetching updates. Defaults to RssWatcher.HTTP.Tesla,
  • :http_client_options - options for the above client. Default to []. See adapter module for configuration options.

Examples 

{RssWatcher,
  url: "http://example.com/rss",
  callback: {Notifications, broadcast, ["#channel_id"]},
  refresh_interval: 60
}

{RssWatcher,
  url: "http://example.com/rss",
  callback: fn xml -> Notifications.broadcast(xml) end,
  refresh_interval: 60
}

{RssWatcher,
  url: "http://example.com/rss",
  callback: &Notifications.broadcast/1,
  refresh_interval: 60
}